


My Brother's a What?

by randomfills (spnfanatic)



Series: In Kansas [1]
Category: Supernatural
Genre: A/U, Alpha Castiel (Supernatural), Alpha/Beta/Omega Dynamics, Beta Sam Winchester, Bottom Dean Winchester, Domestic, Established Castiel/Dean Winchester, Jealous Sam Winchester, Jealousy, M/M, No Hunting, Omega Dean Winchester, Other Additional Tags to Be Added, POV Sam Winchester, Switch Sam Winchester, Top Castiel (Supernatural), Top Sam Winchester, WIP, Wincestiel - Freeform, some gender roles, some non traditional a/b/o, switch castiel (supernatural)
Language: English
Status: In-Progress
Published: 2020-05-12
Updated: 2020-12-07
Packaged: 2021-03-03 04:21:55
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,905
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24138811
Author URL: https://archiveofourown.org/users/spnfanatic/pseuds/randomfills
Summary: AU: A/B/O. Sam left Kansas years ago. Now he was back and things had changed. Including his brother. And it turned out, all of these years, Dean had been keeping something from him. Something huge. Established Dean/Cas, eventual Dean/Sam/Cas
Relationships: Castiel/Dean Winchester, Castiel/Dean Winchester/Sam Winchester, Castiel/Sam Winchester, Dean Winchester/Sam Winchester
Series: In Kansas [1]
Series URL: https://archiveofourown.org/series/1741942
Comments: 26
Kudos: 123





	1. Chapter 1

**Author's Note:**

> Hello. Thought I'd write something a little different. I've wanted to write a wincestiel story for a while now. I was inspired by EW's Supernatural photoshoot videos: https://www.youtube.com/watch?v=fz68krJA_5I, and https://www.youtube.com/watch?v=0QZdCYgYTaQ&t=13s. If you haven't seen them yet, I highly recommend you take a look. The guys are adorable.

Sam was hesitant. He looked down at the address his brother texted him over an hour ago. He looked back up to the large two story house. He was still reeling. He couldn’t quite believe this was the right address, but it was. He double checked. Dean even sent him a picture just in case he got lost or something (more like in case he didn’t believe him). This wasn’t their childhood home. It was different. It had hedges next to the driveway. The front yard was nice and trimmed and didn’t have a tree in the middle of it. The house didn’t very much stand out, it looked like almost every other house in the neighborhood (it belonged in this neighborhood, he realized) but it was well maintained and the door looked recently painted white. He took a deep breath, feeling suddenly nervous. His hands were shaking slightly as he went to push the doorbell. God. This was it. The moment of truth. He hadn’t seen Dean in years, since he left for college, really.

His mind was racing, imagining every possible scenario of this encounter. What did his brother look like now? Was he still going to be the same? Did he still like classic cars and rock music? Was he still in contact with dad? He certainly sounded the same over the phone. He wiped his suddenly sweaty hands on his jeans and waited for an answer. Sam could hear distant footsteps in the house and realized, as he leaned closer, they were getting louder and louder, until, suddenly the door swung wide open and Sam jerked back, surprised to see his brother grinning at him.

His green eyes sparkled with the same mischief, and his hair, though a little longer than Sam remembered, was messy and spiked, like he’d just rolled out of bed, and...Sam looked his brother up and down, noticing the sweats and tee-shirt, his feet bare. He probably did just roll out of bed. Sam frowned at the thought. It was almost noon. He knew Dean liked to sleep in sometimes but it was a monday. Didn’t Dean work? He heard Dean clear his throat and Sam’s head shot back up, startled and a little embarrassed to be caught in a daze. He could feel his cheeks heat up.

Dean’s grin just widened when he saw Sam blush. “Hey, Sammy. Long time, huh?” he said, leaning casually against the door. 

Sam rubbed the back of his neck, feeling suddenly overwhelmed and out of his depth. Oh god. _This was real_ , he suddenly thought. Dean was here, and he was laughing at Sam. He was fucking here. “Hey, Dean,” he mumbled, when he realized his brother was waiting for him to say something. What else could he say? They hadn’t seen each other in what felt like forever, since Sam wanted to make his own way in the world. There wasn’t so much as a phone call in the past few years. Sam had wanted a clean start. 

_And look how that worked out for you_ , he thought bitterly to himself. After all, he was now standing here awkwardly at Dean’s house, about to beg him for a place to stay until he could get back on his feet again.

Sam was still thinking about what to say to his brother, when he heard another set of footsteps echo in the house. He stared at the man who walked into view, coming to rest right behind Dean. Almost on instinct, Sam found himself taking a defensive position, nearly growling out, ‘who’s this?’ But the man beat him to the punch. He smiled at Sam and said, “Ah, you must be Dean’s brother, Samuel.”

Sam felt his muscles tense. This man - stranger - knew Sam _and_ Dean, but Sam swore he’d never seen this guy in his life. He’d remember a man like him. He had the most intense stare he’d ever seen. His eyes were blue, like the ocean, he thought dimly. His hair was also a mess but somehow it didn’t look like it was because he’d just woken up. It suited him. He wore a white collared button up and dark jeans. His hand rested gently on Dean’s shoulder and before Sam could burst with ‘don’t touch my fucking brother’, he saw Dean relax into his touch. It would’ve been almost endearing, if it wasn’t so odd and out of place. 

“My name is Castiel,” the man said. He pulled his brother from the doorway, making room for Sam to step through. “Why don’t you come in, Sam? We’ve been expecting you since the phone call.”

Sam was still on edge but Dean didn’t seem to mind as Castiel led his brother into the living room. He followed them and sat on the couch when Castiel offered it to him. Castiel sat in an armchair across from him and Sam watched as Dean happily sat on the floor at his feet. That was really odd. It was like Sam fell into the twilight zone to be honest.

Suddenly Sam was even more nervous as they made conversation. Castiel knew a great deal about Sam through Dean. He learned that after he left, Dean met Castiel through happenstance. He’d been working at the garage with dad for a while, and Castiel had been a customer with car troubles. Dean showed him some basics on how to keep up with regular maintenance on his car and Castiel felt drawn to him. Sam noticed the blush on his brother’s face before he quickly looked down at the floor as Castiel recounted the tale. He frowned, finding Dean’s behavior off. If he didn’t know any better, Dean was behaving...almost like a teenage girl with her first crush. That image was too weird and Sam shuddered, shaking his head to get rid of it.

Dinner was nice. Dean had been eager to show off his cooking skills and Sam found himself somewhat amused. Growing up, Dean cooked most of the meals but money had been tight so he had never been able to show Sam some of the more extravagant side of cooking. Looking at the large pot of hot, delicious stew, Sam could feel himself salivating. He hadn’t eaten all day. He’d run out of money just getting here, so he couldn’t even stop at a convenient store to grab something cheap and quick. He poured himself a bowl and sat at the table, glad he was going to be able to fully enjoy this.

“Hope you like the stew, Sammy,” Dean said from the kitchen. “It’s one of Cas’ favorite dishes so I try to make it once a month.”

Sam took his first bite and almost moaned from the taste. He could see why. “Holy crap, Dean,” he mumbled, already taking another bite. “I knew you could cook, but wow. This is really good.” And it was. It was one of the most delicious things Sam’s had in awhile.

Dean came by the table to set a bowl down for Castiel. He looked rather pleased with the compliment. “Thanks,” he said as he plopped down on a cushion beside Castiel’s chair. 

Sam swallowed, looking down at Dean in surprise. He hadn’t even noticed the cushion there. Why wasn’t Dean sitting at the table with them?

Castiel’s hand came down to rub the top of Dean’s head. Dean leaned into the touch like it was normal. Sam didn’t quite understand what he was seeing. Soon, Castiel was taking a spoon from the bowl in front of him, full of chicken and rice and veggies, and Dean was opening his mouth. Holy crap. Sam could feel his eyes widening, as he watched the scene for a moment. Castiel was gentle, tender, his gaze loving and Dean, god, he was staring up at Castiel like he was the only one in the room, like Castiel was the only thing that mattered.

Sam swallowed, something in him twisting. He remembered that look. Dean used to look at him that way, when they were kids and Dean was trying to be a good, older brother. He remembered huddling up with Dean late at night when he couldn’t sleep because he had a bad dream. It was weird to see Dean looking at someone else, someone who wasn’t Sam, like that. It...hurt.

Sam had to look away. He stared down at his own bowl, suddenly less hungry. Dean and Castiel were sharing an intimate moment, and Sam was intruding in their life and all he could think about was how it hurt to see Dean happy with someone else. 

Something in the back of his mind said almost snidely, _what right do you have to be jealous? You left him._ And that was the truth.

It didn’t make the hurt and jealousy go away though.

Could Sam get any more pathetic?


	2. Chapter 2

**Notes for the Chapter:**

> Wow thanks so much for all the comments and kudos. Here's the next chapter.

They finished eating dinner and Sam went to help his brother clear the table but before he could even pick up his plate, Dean had already taken it and stacked it in a neat pile. He grinned at Sam and said, “It’s fine, Sammy. I got it.”

Sam opened his mouth to protest but one look from both Dean and Castiel told him it would be futile. He watched in a slight daze, confidence all but gone, as his brother and some stranger ( _to you, not Dean_ , a voice in his head whispered back) grabbed the stack of dirty plates and utensils to the kitchen. Not sure what else to do, he trailed them slowly. Suddenly he was reminded of how he was when he was a kid and he used to tail Dean around like a lost, little puppy. He was out of his depth here, drowning in a large ocean. Here he was, after nearly four years of college, dropping out just before he could make it to law school because he suddenly realized he didn’t want to be a lawyer anymore. Maybe he never wanted to be a lawyer to begin with.

He had gone no contact with both his dad and Dean all four years. Had a little fling with a lovely college freshman named Jess, and when she decided she wanted different things, like a coward, he’d cut her off, just like everything else in his life. He remembered half way through pre-law, he’d come across Dean’s Facebook page and for a week straight, had been stalking his brother’s pictures and wall. There’d been more than a few times where he’d wanted to contact Dean. He missed his brother and college had been hell. It’d been one of the loneliest times of his life when it should’ve been the most fun.

Honestly, he wasn’t sure what he’d been hoping for when he decided to just call Dean. In the back of his mind, he didn’t really think his brother would keep his old number. He thought Dean would’ve changed it by now. Four years was a long time. But even just being here for a couple hours, watching his brother and this stranger interact with each other, with Sam, he could see that maybe a part of Dean had changed, but a larger part stayed the same. The selfish part of Sam was kind of glad of that. The core of Dean didn’t change no matter where he was placed, no matter who he was with. It made it easier for Sam to be able to read him.

Dean rinsed off the dishes and placed them in the dishwasher and Sam found himself leaning against the counter, watching as Castiel walked to stand behind him. Sam didn’t like the familiar closeness they shared but he had to remind himself that Dean wasn’t fighting his advance. In fact, they looked like they’ve done this a thousand times, maybe more. Dean shut off the faucet and he was leaning in with a soft sigh and Castiel was wrapping his arms around his brother and Sam felt a twinge in his chest. It hurt. It fucking hurt.

Castiel's body draped over Dean's like a blanket, as if he was trying to shield Dean from the world. From _Sam_.

The two stood there for what felt like forever. Sam shivered as he felt a cool breeze and he cleared his throat, hoping they could congregate into the living room. Castiel turned to look at Sam with such an intensity that Sam wasn’t backed into a wall, he probably would’ve taken a stumbling step back. 

Instead, he held his gaze long enough to say, “Uh, I know you two are having a moment, and I don’t want to be that guy, but um, it’s getting pretty cold in here, so, uh, I’m going to go back to the other room...if you don’t mind.” He could feel his face heat up as he stumbled over his words and he was about to turn and run out, but Castiel’s grin kept Sam somehow rooted to where he was standing. He could practically hear his heart beat faster in his chest.

“Of course, Samuel,” he said and reluctantly let go of Dean. 

Dean whirled around and caught Sam’s eye, grabbing onto Castiel’s neck before he could pull away further. He grinned, showing Sam his perfect white teeth, and Sam swallowed. “We’ll be with you in just a minute, little brother,” Dean said, before pulling Castiel into a deep kiss.

Sam ran out like his hair caught fire. 

It wasn’t like Sam didn’t think Dean was capable of a relationship. His brother was by no means a virgin. Since he’d presented as a beta at fourteen, Dean had a girlfriend almost on rotation every other week from the time of his presentation to the time Sam hit sophomore year of high school. There was an occasional boyfriend snuck in there somewhere, Sam was almost sure. 

His brother’s longest ‘relationship’ had been a girl named Cassie Robinson, a sweet girl who Dean liked to gush about to him when he thought Sam would listen. It ended up being two whole years before one of them dumped the other. Sam didn’t remember who did the dumping, just that Dean had been a bit mopey for a few weeks before he seemingly bounced back.

He waited on the couch for a few minutes before he saw his brother hovering nearby. Castiel wasn’t anywhere in sight and Sam frowned as he looked around. Dean walked over and sat on the other side of the couch.

“Where, uh, did that guy go?” Sam asked, scratching the back of his neck, still looking for the man. “Castiel, right?”

“Oh, Cas thought it’d be better if he left us to catch up. After all, we haven’t seen each other in a while,” Dean said with a shrug. He looked down at his hands, flexing his fingers.

“Yeah, four years,” Sam said quietly. He swallowed, suddenly nervous to be left alone with his brother. Dean was probably itching to ask him questions, things Sam wondered if he had answers to. 

They lapsed into silence. It was more uncomfortable than Sam realized it could be. They were brothers. They’d been close as kids. Sam vaguely wondered what happened. How did they drift apart? Had it been Sam?

“So, uh, how was Stanford, Sammy?” Dean’s voice snapped Sam out of his thoughts.

He blinked, suddenly back into reality. Dean had stopped picking the grime from his fingernails and was watching Sam now. He wondered if it was his imagination or if there was an underlying accusation in Dean’s voice.

_Why are you intruding on my life and not back at Stanford? You’d been good without me for four years so what gives?_

_Or maybe it was just a genuine question_ , Sam thought to himself, biting the bottom of his lips. Dean wouldn’t actually think that of him, right?

“It was, um, good,” he said finally, clearing his throat awkwardly. His throat suddenly felt dry and he wished he had a glass of water to distract himself from the conversation.

Dean must have seen something on his face and decided to take pity because he stood up, still looking at Sam thoughtfully, and asked, “You okay there, Sam? You look like you might need some water. I can get us some.”

“Yeah, that’d be great actually,” Sam said, lurching to his feet. At Dean’s quizzical look, he added, “I’ll come with you. If you don’t mind the company.”

“Uh, sure, not at all,” Dean told him and led the way back to the kitchen.

As Dean poured them both some water, Sam couldn’t help but blurt, “So I know you said you met that guy, uh, Castiel, when I left, but you know he’s an alpha, right, Dean?”

Dean stared at him for a long moment. His face clearly conveyed one of shock and Sam wondered if he stepped too far. He opened his mouth to backpedal. It was just meant to be an observation. The way Castiel acted, even with a low sense of smell that came with being a beta, it was easy to tell if you knew what you were looking for and Sam had taken his fair share of gender study classes back in college.

Dean’s lips curled into a grin and he burst out in a fit of laughter. “Yeah, Sammy, I know. I knew what Cas was since we first met, dude.”

 _Of course, Dean knows. Wait. What?_

Sam blinked, his mouth clamped shut in surprise. “You know?” _And you're still going out with him?_ he wanted to say but didn't.

“Well, duh, and it doesn’t matter. Alpha or not, he’s funny and charming and we just clicked,” Dean said, grabbing his glass and taking a sip of water. He was still watching Sam, though a tiny trace of the grin was still there. “Anything else you wanna know about my love life, Sammy? Might as well get all the awkward parts out of the way before I send for Cas again.”

Sam took a large gulp of his water and pondered. There were a lot of things he wanted to ask Dean, but it seemed inappropriate considering he just showed up at their doorstep out of the blue, asking for help. He set the empty glass down and shook his head. He’d save the questions for another time. 

Dean raised an eyebrow, not believing Sam for a minute. He had always been a terrible liar. Still, he shook his head and stood his ground. “Look, I do have a lot of questions still, but they can wait, Dean,” he said.

Dean looked at him for a moment longer, looking wholly unconvinced, but Sam stubbornly kept his mouth shut. 

"Okay, fine." Dean sighed, then he leaned forward and pulled Sam into a hug, nuzzling his neck affectionately, “Fuck. I missed you, you know. You have no idea how fucking happy I was when I saw your number calling.” He chuckled into Sam’s collarbone, his fingers curling into his shirt.

Sam gulped nervously. His brother was being uncharacteristically affectionate and Sam wasn’t sure what to do. He hadn’t been this close to Dean since they were kids, before they both presented. Then suddenly he caught whiff of Dean’s scent. It was faint but it was there. He froze.


	3. Chapter 3

“Dean?” Sam’s mouth was the only thing working at this point (or not working depending on how you viewed it). He jerked back, pulling away from Dean when he didn’t move, seemingly oblivious to Sam’s distress. He knew that scent, had caught enough of it in college to differentiate between smells. Sure, betas didn’t have a strong sense of smell like alphas or omegas but that didn’t mean they couldn’t smell at all. Each of them had a unique kind of scent and fuck, Dean didn’t smell at all like a beta this close up.

He smelled like...like cinnamon and apples and hints of roses. But then there were traces of Dean in the mix too. The familiar scent of leather jackets and Dean’s own natural musk that Sam remembered from _before_. And Sam’s so taken back, his thoughts flying a million miles an hour, that he hadn’t even noticed Dean had taken a hesitant step back, staring at him like he might eat him, cautious and guarded. But that didn’t matter. None of it seemed to matter. Because Dean smelled like an omega. And that couldn’t be. Right? Sam would’ve noticed. He would’ve known. Dean would’ve told him. Dad would’ve said something. No one would’ve hid it. Not for all these years. Since Dean presented. And that was over a decade ago.

“Are you okay, Sammy?” Dean asked after a minute. He looked confused, was probably wondering why Sam had jerked back from him like that. His eyes were a little glassy as he studied Sam from afar, before finally taking a step forward and reaching his hand out to rest on Sam’s shoulder.

Sam stiffened at the movement. He wanted to shake his brother’s hand off. He lied. He lied to Sam. For years. But _why_? “You smell like an omega, Dean,” he blurted out before he could stop himself.

Dean’s eyes went wide and his lips parted, like he wanted to say something, but nothing came out. Instead he let his hand drop to hang limp by his side. And Sam, Sam didn’t move, didn’t say a word. Didn’t know what to say. Because the look on Dean’s face was enough to make it clear. Dean was an omega. He lied. He fucking lied to Sam. Hid his gender for over a decade. Sam had no fucking idea. 

“So you are an omega then,” Sam found himself saying. He curled his fingers, could feel the nails digging into his palms. “All these years, Dean. You and dad said you were a beta. You _pretended_ you were a beta.”

God. Sam felt like an idiot.

“Sam, wait.” Dean reached out for him suddenly and Sam wanted to back up. He stopped when he noticed Sam flinching back from him. Hurt flashed through his eyes for a second and Sam couldn’t help the anger creeping up. Really? Dean thought he had the right to be upset with him when he was the one who lied and pretended to be something he wasn’t? He lied to Sam’s face. He lied, lied, lied. 

“No!” He shouted, startling them both. Dean’s eyes went wider (how was that even possible?) and he shut his mouth immediately and bared his neck, a sign of submission that only further confirmed his omega status. It would’ve been enough to quell the rage Sam was feeling swirling in him. Had he been an alpha at least. But it only made him angrier. This was undeniable proof that Dean lied about what he really was. _Who_ he really was. “You _lied_ to me, Dean. You had so many chances to come clean and you never did,” he said. He could feel the bitterness in his voice, could almost taste it. The question ‘why, why would you lie to me,’ was on the tip of his tongue. He didn’t understand why Dean would lie to him, why he’d smile and laugh and pretend like everything was normal all those years ago when he had been hiding such a big secret, hiding who he was. But then he noticed Dean taking another step back, almost shrinking away from him, and it was like Sam had just been hit in the gut, his anger all but drained away at that scared look on his brother’s face. 

Instinct made him reach out for his brother, to wrap him up in his arms and tell him he didn’t mean to get mad, but before he could ever touch Dean, Castiel stormed into the kitchen like a freaking tsunami, his scent overwhelmingly protective and angry, his nostril flaring, his lips pressed in a thin line as he glared at Sam. Sam took a step back as Castiel pulled Dean, his _brother_ , close to him, his arms wrapping around him like a protective shield. Sam stood frozen as he watched Castiel dip his head to rest on Dean’s shoulder. He watched as Dean slowly uncurled himself and relaxed under his alpha’s touch. He felt jealousy flare in the pit of his stomach as he forced himself to watch this small display of affection. That used to be Sam and Dean when they had been kids. Sam wished he could move his legs so that he could flee from this place, where Dean clearly had a life away from his brother, where he had forgotten the bond they used to share. His legs felt like jelly though. If he took one step, he was sure he’d collapse and honestly, as much as he wanted away from here, he really didn’t want the spotlight that collapsing to the floor would bring. As much as it hurt to watch Dean smiling so brightly at this stranger, he didn’t want to face Castiel’s ire.

It didn’t seem to matter though because eventually, after Dean calmed down, Castiel’s attention found its way back to Sam, who stood straight and stiff. Anger at being lied to had drained away and made way for guilt. Castiel reluctantly stepped away from Dean and was regarding Sam with a hard glint in his amazingly blue eyes. 

Sam had never seen anyone look as protective and powerful as Castiel, save for a couple times when Dean found out a couple kids had bullied Sam back in grade school. Even their father never looked at anyone like the way Castiel was looking at Sam. It was more than a little unnerving and Sam found himself taking another step back as Castiel started to slowly advance on him. Dean reached out and grabbed hold of Castiel’s arm, “Go easy on Sammy. He didn’t know.”

Castiel turned to look back at Dean. “It doesn’t matter whether he knew of your designation or not. That doesn’t excuse him yelling at you, Dean. That doesn’t excuse him scaring you,” he spat, before whirling back to glare at Sam. “And _you_! How fucking dare you step foot into our house thinking you can just scare the shit out of the brother _you_ left for dead in the first place.”

Sam didn’t know how to respond to that. Shit. He never meant to scare Dean. He had been hurt, incredibly hurt, that Dean lied to him growing up and he didn’t even know what for. But Castiel was right. He was the one who left Dean behind. He left to go to college, to make something of himself, and didn’t even want to stay in contact with anyone. He thought a clean cut was something that was necessary. Start over somewhere no one knew him, marry Jess and become a successful lawyer, have kids and buy a big house. He dreamt of the kind of lifestyle where he didn’t have to worry about money like his dad, where he could learn to be happy without worrying he’d never get out of his older brother’s shadow. But life happened and things fell apart before Sam’s eyes and here he was standing in his brother’s kitchen, making a fool of himself because he was jealous of Dean’s life and that his brother clearly moved on from Sam, and he clung to the one thing that seemed like such a flaw in his otherwise perfect brother. He became angry because the feeling was easier, _familiar_.

It was such an obvious mistake to come here. “I, uh, I’m sorry. I didn't mean to,” Sam said finally because he had no idea what else he could say.

Castiel looked ready to say something but he was cut off when Dean hunched over, an agonized gasp ripping from him as he clutched his stomach. Castiel hurried back to Sam’s brother’s side and dropped to his knees as he tried to get one of Dean’s arms over his shoulder. He lifted Dean to his feet as Sam stood there, confused and concerned, and torn between reaching to help steady his brother or staying where he was. “Is...is he okay? What’s wrong with him?” Sam asked, wanting nothing more than to help.

The look Castiel sent him was scathing. “If you hadn't been so completely self-absorbed, you would have smelled his heat. I’m going to help him upstairs now.” He didn’t wait for Sam to respond. He helped Dean out of the room, his voice soft and tender as he whispered into Dean’s ear, “It’ll be okay, love. I’m just helping you to our room so that you can rest for the evening.”

As soon as the pair was out of sight, Sam collapsed to the floor. He never felt like such a complete and utter jackass, and a failure of a brother than in this moment. It was so very obvious that Sam was an outsider, an unwanted guest in his brother’s life and if he had been the good little brother Dean deserved, he would have quietly got up and gathered his things and been on his way. But Sam was selfish and he hadn’t seen his brother in years and maybe that was his fault...no, it was _definitely_ his fault, but god did he miss Dean. He missed his older brother with every fiber of his being.


End file.
